The answer to 'how much to replace generator installation in Illinois' is that the cost can vary widely depending on several factors. Generally, a full generator installation in Illinois can range from $3,000 to $15,000 or more, depending on the size and type of generator, the complexity of the electrical work required, and the location.
Factors that influence the cost include the generator model and size, the accessibility of the installation site, the need for electrical panel upgrades, permits and inspections, and the labor rates in your local area. It's important to get quotes from multiple licensed electricians in your region to get an accurate estimate for your specific project.